Complex Polymer Structures Research Articles

Low-cost method to reduce interlayer voids in material extrusion: in situ layer-by-layer solvent treatment

Material extrusion (MEX) is worldwide known as one of the most flexible additive manufacturing (AM) technologies for the fabrication of complex polymeric structures. However, the extremely high geometrical freedom has a price to pay: the presence of interlayer voids between consecutive extruded layers is the main backwards of MEX technology. Interlayer voids make 3D printed parts weaker (poor mechanical properties) compared to polymeric components fabricated by means of counterpart processes (i.e., injection molding). The present research work introduces a novel approach for the reduction of voids based on the layer-by-layer application of solvent vapor during the fabrication process, to smooth every single deposited layer. In this way, the new extruded layer has a greater area to bond with the previously extruded layer, resulting in an overall reduction of the porosity. The proposed approach is cost-effective, and it is based on the stop and go method enabled by MEX technologies: the fabrication process is paused after every layer, and when the solvent treatment is performed, the 3D printing process is resumed. The effectiveness of the layer-by-layer solvent vapor approach was evaluated, thereby resulting in a great reduction of the void density and average void area of 96%, and 79% respectively, and an increase of the wetting factor of 34%. Such findings pave the way for the exploitation of the proposed approach for the fabrication of complex structures with a reduced number of voids to be employed as structural components.

Non‐linear functional polymers containing selective/cleavable bonds: Synthesis and their biomedical applications

AbstractThe growing interest in functional materials has resulted in the emergence of smart polymers, demonstrating practical performance in various applications especially for biomedical purposes. The properties of functional polymers are mainly determined by the presence of functional groups that differ from those in the main chains. While some polymers are naturally active and considered functional, others require modification for enhanced impact and functionality. Many functional polymers typically have a linear backbone, but very recently the attention has been shifted towards those with specific topologies and architecture, for example, bottlebrushes, stars, dendritic polymers, and gels. Over the past few years, there has been a rising emphasis on integrating selective bonds into complex polymer structures to enhance chain scission in single macromolecules. This review captures the most recent and promising approaches to the design of non‐linear functional polymers containing selective/cleavable bonds and discusses the potential of these materials for biomedical applications.

Influence of wall thickness on mechanical properties and porosity of additive manufactured polymer-based porous structures for fibula bone regeneration

In the recent past, Bone tissue engineering (BTE) has become a potentially effective solution for repairing bone defects. In the meantime, various fields, such as material science, additive manufacturing, and clinical medicine, are interlinked in the fast-emerging field of bone tissue engineering. Additive Manufacturing (AM) is a unique technology that accumulates content rather than waste materials in the form of chips. AM techniques like selective laser sintering (SLS), commonly used to create complex polymer structures, allow for the direct fabrication of complex structural implant components for use in BTE. However, the wall thickness of the product limits the SLS systems. In detail, research into the influence of wall thickness on mechanical properties and scaffold porosity is required to develop such lightweight and complex structures. In this study, Polyamide12-based bone Scaffolds were fabricated using the SLS technique by varying the wall thickness ranging from 0.9 mm to 1.10 mm in steps of 0.05 mm. Compression tests, porosity, scanning electron microscopy, and differential scanning calorimetry were conducted on the fabricated specimens. The studies demonstrated that the higher wall thickness benefits in reduction of porosity. The sample fabricated with a wall thickness of 1.1 mm has about 76% less porosity than the sample fabricated with a wall thickness of 0.9 mm. In addition, the study also found that compression strength decreases as porosity increases. The compressive strength of the scaffolds has been measured to be between 45.62 and 90.67 MPa for a wall thickness between 0.90 and 1.10 mm. The maximum compressive strength of a porous polyamide specimen is 90.67 MPa at a wall thickness of 1.10 mm. The fabricated samples with wall thicknesses of 0.9 and 0.95 mm were not mechanically stable, as their compressive strength values were lower than the compressive strength of human fibula bone (68 N/mm2).

The Power of Automation in Polymer Chemistry: Precision Synthesis of Multiblock Copolymers with Block Sequence Control.

Machines can revolutionize the field of chemistry and material science, driving the development of new chemistries, increasing productivity, and facilitating reaction scale up. The incorporation of automated systems in the field of polymer chemistry has however proven challenging owing to the demanding reaction conditions, rendering the automation setup complex and costly. There is an imminent need for an automation platform which uses fast and simple polymerization protocols, while providing a high level of control on the structure of macromolecules via precision synthesis. This work combines an oxygen tolerant, room temperature polymerization method with a simple liquid handling robot to automatically prepare precise and high order multiblock copolymers with unprecedented livingness even after many chain extensions. The highest number of blocks synthesized in such a system is reported, demonstrating the capabilities of this automated platform for the rapid synthesis and complex polymer structure formation.

Single-Particle Tracking in Poly(Ethylene Glycol) Diacrylate: Probe Size Effect on the Diffusion Behaviors of Nanoparticles in Unentangled Polymer Solutions.

A thorough understanding of the relevant factors governing the transport of nanoparticles in poly(ethylene glycol) diacrylate (PEGDA) is crucial for many applications utilizing this polymer. Here, single-particle tracking (SPT) was used to systematically investigate the role of the probe size (3-200 nm) on the diffusion behaviors of individual fluorescent nanoparticles in semidilute and unentangled PEGDA solutions. The quantitative assessment of the SPT data via the recorded single-particle trajectories and diffusion coefficients (D) not only showed that the observed probe dynamics in PEGDA were temporally and spatially heterogeneous, but more importantly that the measured D were observed to be significantly reduced (vs in solvent) and strongly size-dependent. We explained these results based on a modified multiscale model for particle diffusion, built upon well-established hydrodynamics and obstruction theories. We furthermore showed that the presence of steric interactions and probe confinement effects in highly crowded, unentangled PEGDA microstructures can lead to deviations in the single-particle displacements from the expected Gaussian behavior, as revealed by the van Hove displacement distributions and the associated non-Gaussian parameters. This study has demonstrated the power of SPT methods in offering an advanced characterization of the transport characteristics in complex polymer structures, overcoming challenges posed by traditional characterization techniques.

Miscibility and phase behavior of reactively compatibilized poly(lactic acid)/poly(butylene succinate) bio‐blends using various rheological analyses

AbstractThis study focuses on the compatibilization of PLA/poly(butylene succinate) (PBS) blends using mono‐ and multi‐epoxide POSS (MoEpPOSS and MuEpPOSS) nanoparticles, from a rheological point of view for the first time in the literature. The addition of PBS to PLA decreased the complex viscosity, storage modulus, and loss modulus, indicating weak interactions between polymers. However, the incorporation of MoEpPOSS and MuEpPOSS increased the complex viscosity and storage modulus due to the formation of long polymeric chains or complex polymeric structures through interactions between the epoxide groups of POSS and the end groups of the polymers. The effect was more significant with MuEpPOSS because MuEpPOSS has multiple epoxide groups in its cage structure, leading to stronger interactions with the polymers. POSS incorporation resulted in semicircular and arc‐shaped curves in the Cole‐Cole plots, indicating better dispersion, phase homogeneity, and compatibility. The introduction of POSS also influenced the dynamic loss tangent (tan δ) versus frequency (ω) plot. When POSS was introduced, the tan δ peak decreased and shifted to a higher frequency, indicating improved compatibility, and enhanced interfacial adhesion. These findings indicated that the addition of epoxy‐POSS nanoparticles can effectively compatibilize PLA/PBS blends and enhance their rheological properties, potentially improving their overall performance for various applications.

Improving Pulping Performance as Well as Reducing Consumption and Increasing Efficiency via Microbial Consortium Pretreating Bamboo

The bio-refining process of bamboo is more challenging compared to wood due to its dense and stabilized complex polymer structure, as well as its abundance of degradation-resistant components. Consequently, the bio-refining of bamboo requires more energy and time consumption compared to the bio-refining of wood. In this study, co-cultured microorganisms were utilized for the pretreatment of bamboo to improve pulping performance, reduce consumption, and increase efficiency. These microorganisms were constructed by combining environmental microorganisms found in bamboo pulp with Bacillus sp. that were self-screened. The results of 16S rRNA analysis showed that the genera Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota gradually became dominant during the treatment process. Additionally, the PICRUSt results indicated that the co-culture microbial consortium C strategy strengthened key enzyme activities related to the degradation of bamboo lignocelluloses. The microbial consortium pretreatment resulted in removing lignin and hemicellulose at rates of 21.96% and 26.21%, respectively. This process also caused a decrease in the crystalline index, indicating the presence of disordered crystalline regions. This change was beneficial for the subsequent Kraft pulping process. Compared to the conventional bamboo pulp, the yield of pretreated bamboo pulp increased slightly, while the cellulose purity and paper properties were significantly superior. The obtained Kraft pulp, which underwent microbiological pretreatment, met the requirements for superior Kraft pulp products despite a 65 min decrease in cooking time and a 10 °C decline in maximum cooking temperature. This study proves that co-cultured microbial consortium used for pretreating bamboo are beneficial for bamboo Kraft pulping. This approach can be considered environmentally friendly and leads to energy saving and cost reduction in bamboo bio-refining processes.

Lamellar orientation at the surface of isotactic polystyrene thin films analyzed by sum frequency generation spectroscopy.

Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option.

Polymeric structure of the Cannabis sativa L. mitochondrial genome identified with an assembly graph model

Cannabis sativa L. belongs to the family Cannabaceae in Rosales. It has been widely used as medicines, building materials, and textiles. Elucidating its genome is critical for molecular breeding and synthetic biology study. Many studies have shown that the mitochondrial genomes (mitogenomes) and even chloroplast genomes (plastomes) had complex polymeric structures. Using the Nanopore sequencing platform, we sequenced, assembled, and analyzed its mitogenome and plastome. The resulting unitig graph suggested that the mitogenome had a complex polymeric structure. However, a gap-free, circular sequence was further assembled from the unitig graph. In contrast, a circular sequence representing the plastome was obtained. The mitogenome major conformation was 415,837 bp long, and the plastome was 153,927 bp long. To test if the repeat sequences promote recombination, which corresponds to the branch points in the structure, we tested the sequences around repeats by long-read mapping. Among 208 pairs of predicted repeats, the mapping results supported the presence of cross-over around 25 pairs of repeats. Subsequent PCR amplification confirmed the presence of cross-over around 15 of the 25 repeats. By comparing the mitogenome and plastome sequences, we identified 19 mitochondria plastid DNAs, including seven complete genes (trnW-CCA, trnP-UGG, psbJ, trnN-GUU, trnD-GUC, trnH-GUG, trnM-CAU) and nine gene fragments. Furthermore, the selective pressure analysis results showed that five genes (atp1, ccmB, ccmC, cox1, nad7) had 19 positively selected sites. Lastly, we predicted 28 RNA editing sites. A total of 8 RNA editing sites located in the coding regions were successfully validated by PCR amplification and Sanger sequencing, of which four were synonymous, and four were nonsynonymous. In particular, the RNA editing events appeared to be tissue-specific in C. sativa mitogenome. In summary, we have confirmed the major confirmation of C. sativa mitogenome and characterized its structural features in detail. These results provide critical information for future variety breeding and resource development for C. sativa.

Differences between water-soluble and water-insoluble melanin derived from Inonotus hispidus mushroom.

Melanin is a natural pigment with a high content and a complex polymer structure. In this study, both water-soluble and water-insoluble melanin were obtained from the fruiting bodies of the mushroom Inonotus hispidus, and scanning electron microscopy (SEM), ultraviolet (UV) absorption, Fourier transform infrared (FTIR) spectroscopy, elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, pyrolysis gas chromatography mass spectroscopy (Py-GCMS), and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS/MS) were used to analyze the water-soluble and water-insoluble I. hispidus fungal melanin (IHFM). Differences in the chemical composition and structure of I. hispidus fungal melanin (IHFM) were found. Studies showed that both have a maximum absorbance at 226nm, and the maximum mass-to-charge ratios are [M+H] + m/z=272.2434 and 272.0308, respectively. Elemental analysis revealed that they both contain C, H, N, O, and do not contain sulfur, which is only found in eumelanin. The differences between water-soluble and water-insoluble IHFM may relate to the following factors: (i) the microscopic particles of water-soluble IHFM are relatively small, the arrangement is relatively neat, and they contain a large quantity of benzene, phenol, and indole compounds; and (ii) the microscopic particles of water-insoluble IHFM are larger and the arrangement is irregular. The types and quantities of benzene, phenol, and indole compounds are relatively small, rich in a variety of sugar monomers, and may be insoluble in water due to the presence of a greater number of aliphatic groups. Studies have found that water-soluble IHFM has good cellular antioxidant activity, can reduce oxidative damage by hydrogen peroxide (H2O2) on LO2 cells effectively and can significantly reduce the level of intracellular reactive oxygen species (ROS) to protect the liver. These results are beneficial in order to develop applications of melanin in the food industry and in other fields.

The High-Temperature Soft Ferromagnetic Molecular Materials Based on [W(CN)6(bpy)]2−/− System

The synthesis of molecular materials with magnetic properties, in particular ferromagnetic properties, has been the subject of interest in coordination chemistry for decades. In the last three decades, research has accelerated, as it has emerged that creating bridging systems based on cyanido ligands is a good and relatively simple way to create complex polymer structures exhibiting magnetic properties. Based on many years of personal experience in the field of the synthesis of polycyanido systems, supported by comprehensive structural analysis, a simple method of transforming cyanido complexes into soft ferromagnetic materials with a Curie temperature (TC) higher than the thermal decomposition temperature, usually above 150 °C has been developed. Two soft ferromagnetic materials based on zinc and cadmium hexacyanido salts in the system with [W(CN)6(bpy)]2−/− anions are presented. The crystal structures (X-ray single crystal as well as XRD) of the precursors and the properties of the ferromagnetic materials are discussed. Most importantly, a patented method of synthesizing this type of material, based on which we obtain more than 80 soft, high-temperature ferromagnetic compounds, which proves the wide spectrum of this method, is also presented.

Characterization of a 30 µm pixel size CLIP-based 3D printer and its enhancement through dynamic printing optimization.

Resolving microscopic and complex 3D polymeric structures while maintaining high print speeds in additive manufacturing has been challenging. To achieve print precision at micrometer length scales for polymeric materials, most 3D printing technologies utilize the serial voxel printing approach that has a relatively slow print speed. Here, a 30-µm-resolution continuous liquid interface production (CLIP)-based 3D printing system for printing polymeric microstructures is described. This technology combines the high-resolution from projection microstereolithography and the fast print speed from CLIP, thereby achieving micrometer print resolution at x103 times faster than other high-resolution 3D printing technologies. Print resolutions in both lateral and vertical directions were characterized, and the printability of minimum 30 µm features in 2D and 3D has been demonstrated. Through dynamic printing optimization, a method that varies the print parameters (e.g. exposure time, UV intensity, and dark time) for each print layer, overhanging struts at various thicknesses spanning 1 order of magnitude (25 µm - 200 µm) in a single print are resolvable. Taken together, this work illustrates that the micro-CLIP 3D printing technology, in combination with dynamic printing optimization, has the high resolution needed to enable manufacturing of exquisitely detailed and gradient 3D structures, such as terraced microneedle arrays and micro-lattice structures, while maintaining high print speeds.

ReaxFF Force Field Development for Gas-Phase hBN Nanostructure Synthesis

Two-dimensional (2D) hexagonal boron nitride materials are isomorphs of carbon nanomaterials and hold promise for electronics applications owing to their unique properties. Despite the recent advances in synthesis, the current production capacity for boron nitride (BN) nanostructures is far behind that for carbon-based nanostructures. Understanding the growth mechanism of BN nanostructures through modeling and experiments is key to improving this situation. In the current work, we present the development of a ReaxFF-based force field capable of modeling the gas-phase chemistry important for the chemical vapor deposition (CVD) synthesis process. This force field is parameterized to model the boron nitride nanostructure (BNNS) formation in the gas phase using BN and HBNH as precursors. Our ReaxFF simulations show that BN is the best of these two precursors in terms of quality and the size of BNNSs. The BN precursors lead to the formation of closed BNNSs. However, BNNSs are replaced with complex polymeric structures at temperatures of 2500 K and higher due to entropic effects. Compared to the BN precursors, the HBNH precursors form relatively small, flat, and low-quality BNNSs, but this structure is less affected by temperature. Additives like H2 significantly affect the BNNS formation by preventing closed BNNS formation. Our results show the ReaxFF capability in predicting the BN gas-phase chemistry and BNNS formation, thus providing key insights for experimental synthesis.

Preparation of Homopolymer, Block Copolymer, and Patterned Brushes Bearing Thiophene and Acetylene Groups Using Microliter Volumes of Reaction Mixtures.

The synthesis of surface-grafted polymers with variable functionality requires the careful selection of polymerization methods that also enable spatially controlled grafting, which is crucial for the fabrication of, e.g., nano (micro) sensor or nanoelectronic devices. The development of versatile, simple, economical, and eco-friendly synthetic strategies is important for scaling up the production of such polymer brushes. We have recently shown that poly (3-methylthienyl methacrylate) (PMTM) and poly (3-trimethylsilyl-2-propynyl methacrylate) (PTPM) brushes with pendant thiophene and acetylene groups, respectively, could be used for the production of ladder-like conjugated brushes that are potentially useful in the mentioned applications. However, the previously developed syntheses of such brushes required the use of high volumes of reagents, elevated temperature, or high energy UV-B light. Therefore, we present here visible light-promoted metal-free surface-initiated ATRP (metal-free SI-ATRP) that allows the economical synthesis of PMTM and PTPM brushes utilizing only microliter volumes of reaction mixtures. The versatility of this approach was shown by the formation of homopolymers but also the block copolymer conjugated brushes (PMTM and PTPM blocks in both sequences) and patterned films using TEM grids serving as photomasks. A simple reaction setup with only a monomer, solvent, commercially available organic photocatalyst, and initiator decorated substrate makes the synthesis of these complex polymer structures achievable for non-experts and ready for scaling up.

Recent Advances in Diversity-Oriented Polymerization Using Cu-Catalyzed Multicomponent Reactions.

Diversification of polymer structures is important for imparting various properties and functions to polymers, so as to realize novel applications of these polymers. In this regard, diversity-oriented polymerization (DOP) is a powerful synthetic strategy for producing diverse and complex polymer structures. Multicomponent polymerization (MCP) is a key method for realizing DOP owing to its combinatorial features and high efficiency. Among the MCP methods, Cu-catalyzed MCP (Cu-MCP) has recently paved the way for DOP by overcoming the synthetic challenges of the previous MCP methods. Here the emergence and progress of Cu-MCP, its current challenges, and future perspectives are discussed.

Influencing Parameters for degradation of Methylene Blue using the catalyst bentonite supported manganosite MnO synthesized via facile, one-pot Sol-Gel Route

Textile industries consume considerable amounts of water in dyeing process, thus generating the enormous quantities of wastewater. The wastewater is a highly harmful to environment if discharged untreated or partially treated since it contains wide range of hazardous compounds and is also very difficult to treat. The structure of dye residues in wastewater is mostly complex polymeric structures, which is highly resistant to bio-degradation. The Fenton-based advanced oxidation process (AOP) was widely studied to treat recalcitrant organic contaminant and based on the production of OH following H2O2 activation by a catalyst. Manganese oxides are reported to be an active catalyst for degradation of a dye via Fenton process. Herein, bentonite supported MnO (MnO/bentonite) was synthesized via one-pot sol-gel synthesis and its catalytic activity was evaluated for the degradation of methylene blue (MB) using Fenton process. The X-ray diffraction results revealed the formation of the rock–salt MnO manganosite as crystalline phase of manganese oxide. The MnO/bentonite composite displayed higher performance for the degradation of MB than pure MnO. The maximum degradation of MB by MnO/bentonite composite was achieved by evaluating the process variables and compared to MnO (manganosite) as a control. In the optimum condition, the MnO/bentonite composite was able to degrade 92.97 % MB using 15 ml H2O2, 50 mg of catalyst and 25 ml MB (75 ppm) in 100 mL solution of initial MB concentration. Both catalyst concentration and H2O2 concentration seem to play a significant role for the degradation of MB using the composite MnO/bentonite.

Lemna minor L. (Su mercimeği)'de Everzol Lacivert ED’ye Dirençte Salisilik Asitin Rolü

The dyes used in the production of the textile industry are toxic substances that are resistant to biological treatment. Most of them have highly complex polymer structures. Salicylic acid (SA) is an important hormone produced by plants that provides tolerance to many biotic and abiotic stress factors. Duckweed (L. minor L.) are free floating plants. These plants have been used in laboratory toxicological studies by many researchers for reasons such as their high adaptability to aquatic environments, their small biomass and their high ability to accumulate contaminants. The aim of this study was to evaluate some biochemical changes in duckweed (L. minor L.) of 75 ppm, 150 ppm and 300 ppm Everzol Navy ED (ENED) reactive dyestuff and 0.5 mM SA and ENED application. Total chlorophyll and carotenoid contents were found higher at 0.5 mM SA and 300 ppm dye applied groups on day 7. Peroxidase (POD), ascorbate peroxidase (APX) and Glutathione S-transferase (GST) activities and total glutathione (GSH) content were increased at 0.5 mM SA with ENED application groups. (Superoxide dismutase) SOD and Catalase (CAT) activity increased on days 1, 4 and 7 in both treatment groups. GR activity decreased in dye applied groups and 0.5 mM SA with dye applied groups on day 7. MDA content decreased on day 7 with 300 ppm dye application and 0.5 mM SA and 300 ppm dye application.

History of cyclodextrin-based polymers in food and pharmacy: a review.

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

CHARMM-GUI Polymer Builder for Modeling and Simulation of Synthetic Polymers.

Molecular modeling and simulations are invaluable tools for polymer science and engineering, which predict physicochemical properties of polymers and provide molecular-level insight into the underlying mechanisms. However, building realistic polymer systems is challenging and requires considerable experience because of great variations in structures as well as length and time scales. This work describes Polymer Builder in CHARMM-GUI (http://www.charmm-gui.org/input/polymer), a web-based infrastructure that provides a generalized and automated process to build a relaxed polymer system. Polymer Builder not only provides versatile modeling methods to build complex polymer structures, but also generates realistic polymer melt and solution systems through the built-in coarse-grained model and all-atom replacement. The coarse-grained model parametrization is generalized and extensively validated with various experimental data and all-atom simulations. In addition, the capability of Polymer Builder for generating relaxed polymer systems is demonstrated by density calculations of 34 homopolymer melt systems, characteristic ratio calculations of 170 homopolymer melt systems, a morphology diagram of poly(styrene-b-methyl methacrylate) block copolymers, and self-assembly behavior of amphiphilic poly(ethylene oxide-b-ethylethane) block copolymers in water. We hope that Polymer Builder is useful to carry out innovative and novel polymer modeling and simulation research to acquire insight into structures, dynamics, and underlying mechanisms of complex polymer-containing systems.

3D nonlinear photolithography of Tin oxide ceramics via femtosecond laser

As a wide band gap semiconductor material, tin oxide (SnO2) has been widely used in gas sensing, optoelectronics and catalysis. The complex micro and nanoscale three-dimensional (3D) geometric structures endow the conventional SnO2 ceramics with novel properties and functionalities. Nevertheless, ceramics cannot be cast or machined easily due to their high mechanical toughness and resistance. The additive manufacturing opens a great opportunity for flexibly geometrical shaping, while the arbitrary shaping of SnO2 ceramics at micro and nanoscale is always a challenge. Herein, preceramic monomers which can be polymerized under ultrafast laser irradiation, were utilized to form complex and arbitrary 3D preceramic polymer structures. After calcination treatment, these green-body structures could be converted into pure high-dense SnO2 ceramics with uniform shrinkage, and the feature size was down to submicron. Transmission electron microscopy (TEM) analysis displays that the printed SnO2 ceramic nanostructures can be nanocrystallized with grain sizes of 2.5 ± 0.4 nm. This work provides the possibility of manufacturing 3D SnO2 ceramic nanostructures arbitrarily with sub-100 nm resolution, thus making it promising for the applications of SnO2 in different fields.